Anastigmatic objective for photography and projection



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Feb. 25, 1936. R RlcHTER 2,031,792

ANASTIGMATIC OBJECTIVE FOR PHOTOGRAPHY AND PROJECTION Filed July 25,1934 3 Sheets-Sheet l T 2 O2 9 x2255 r, 11.25 d1 444 P 16.55

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[-1 I L4 L12 8 L3 Inventor:

Search Room Feb. 25, 1936. R RlcHTER 2,031,792

ANASTIGMATIC OBJECTIVE FOR PHOTOGRAPHY AND PROJECTION Filed July 25,1934 3 Sheets-Sheet 2 p, 42. 63 4. e9 I 47. I a r 10.05 05 H, 0.29, 12.1538 I 1 0.02 P7 I 18- d I 5 12.93 4

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Inventor:

Search Room Feb. 25, 1936. R. RICHTER 2,031,792

ANASTIGMATIC OBJECTIVE FOR PHOTOGRAPHY AND PROJECTION Filed July 25,1934 3 Shuts-Sheet 3 I 2 I 2 I 8 8 2 1 1 I I I I l 1 1 I 1 I I I I I 1 II I I I I I, I l l I I l I I 1 I I l I I, I I 2 I I 4 I 1 I 1 1 1 1 1 1I I I I 1 1 1 1 1 l 1 I 4 z l 2 I I 1 I I "D I V 64.0

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Inventor:

FM Z1141 UNITED STATES Search 3 PATENT OFFICE ANASTIGMATIC OBJECTIVE FORPHO- TOGRAPHY AND PROJECTION Robert Richter, Jena, Germany, assignor tothe firm of Carl Zeiss, Jena, Germany Application July 25, 1934, SerialNo. 736,880 In Germany July 26, 1933 9 Claims.

The present invention concerns anastigmatic objectives for photographyand projection having a pair of meniscal members bounded by air ateither side of the locus of diaphragm. Each of the pairs consists of adiverging and a converging member. The diverging member of each pair andthe concave surfaces of all members face the locus of diaphragm andthose two surfaces of each pair which face each other are differentlycurved. The locus of diaphragm is understood to be that point in theoptical axis of the objective in the vicinity of which the principalrays of the inclined pencils of rays intersect the optical axis and nearwhich the aperture diaphragm is usually placed when the restriction ofthe aperture is not efiected by the edges of the mounts of the lenses.The known objectives of this kind have either only the said two pairs ofmembers or they have other members for improving the correction. In theknown objectives, the distance apart of the vertices of the two surfacesimmediately in front and behind the locus of diaphragm has been smallerthan approximately one half the arithmetical means of the radii ofcurvature of these two surfaces.

According to the invention, the capacity of this kind of objectives isconsiderably increased by increasing the distance apart of the twoconcave surfaces in the vicinity of the locus of diaphragm, the saiddistance being made greater than four fifths of the arithmetical meansof the radii of curvature of these two concave surfaces. There is thusobtained an objective which has a great rapidity and may be used as awide-angle lens, since it may be corrected spherically, chromatically aswell as astigmatically much better than any objective known so far.

The angle of view can be increased with these objectives by more thanwhen the said distance apart is made greater than the arithmetical meansof the radii of curvature of the two concave surfaces near the locus ofdiaphragm.

To obtain as great an angle of view as possible, it is advisable to makethe objective consist of only four single lenses,. the locus ofdiaphragm having at either side one converging and one diverging lens,and the refractive indices of the diverging lenses being suitablygreater than 1.65. It is advantageous to provide that the diverginglenses are near the locus of diaphragm and have central thicknesssmaller than 2% of the focal length of the objective.

When the objectives are symmetrical to the locus of diaphragm, theimages of objects at great distances are generally distorted a little,since, as a rule, only reproduction in natural size is not affected bythe distortion of symmetrical objectives. The principal aim ofphotography is, however, to reproduce objects at a great distance, andthat of projection is to project near objects at a great distance. Toavoid distortion, the objectives are generally made dissymmetrical. Withthe objectives according to the invention it has been achieved to removethe distortion in the case of objects at infinity by makingdissymmetrical only one pair of members and maintaining the symmetry ofthe other pairs. This advantage is very significant because it is madepossible to use a symmetrical pair of flint glasses, whose manufactureoffers considerable difllcul- 2o ties, in the interior and to neutralizethe distortion by a dissymmetry of the two converging members.

The objectives according to the invention may be also constructed insuch a manner that the distortion is removed regardless of the imaging25 scale, as is desired for instance in the case of objectives forevaluating distorted photogrammetric photographs. This is achieved bymaking the objective consist not only of four members whose concavesurfaces face the locus of diaphragm but also of at least one exteriorlens whose radii of curvature are, absolutely, greater than the focallength of the objective or of an exterior plano-parallel plate. In thiscase a distortion is avoided also when the objective is symmetrical, usebeing made of a pair of additional lenses or plates.

The accompanying drawings and the following tables refer to threedifferent objectives according to the invention. In the drawings,Figures 1, 2 and 3 illustrate sections through, and containing theoptical axes of, the objectives according to the first, the second andthe third constructional example, respectively.

The first constructional example, which is il- 45 lustrated by Figure 1,consists of a symmetrical objective having four lenses L1, Lo, Lo, andL4, whose sides facing the locus of diaphragm are concave. The focallength of the objective is ,fn=66.0 millimetres. The objective has agood 5o central definition also when the ratio of aperture is 126.3, theanastigmatic correction covering a field of view of 100 with only veryslight intermediate errors. The dimensions in millimetres and the kindsof glass of this objective are as follows:

1mm fi 1m Kinds of glass Ti-1L25 d1=4.44 lip-1.6111 v-BOA "-16.55

dx= 0.5 1ID=L7172 I=29.5 n- 7.35

da= 0.5 m =l.7172 r-29.5 n- 9.094

The second constructional example (Figure 2) has a focal length offn=75.7 millimetres and consists of four lenses L1, La, La and L4. Thetwo exterior lenses L1 and Li are dissymmetrical and the two interiorlenses L2 and L: are symmetrical to the locus of diaphragm. Thisobjective has the following dimensions:

Thicknesses and Radn distances Kinds of glass d1- 4. 89 nn=1. B185 w-60.5 "-17. 70

d:- 0.5 rip-1.7261 r-29.0 n- 8.29

d 0. 5 fin-1.7261 v=29. 0 "-10. 05

d4- 5. 07 nil-1.0185 r=60.5 n-l2. 93

Figure 3 of the drawings represents a symmetrical objective which hasnot only four lenses L1, La, La and L4 whose sides facing the locus ofdiaphragm are concave but also two exterior piano-parallel plates P1 andP2- With this constructional example, the distortions corresponding tothe imaging scales 1:1 and :1, respectively, are neutralized to a smallintermediate error. The focal length of this objective is jn=66.1millimetres. The objective may be also used with the ratio of aperture1:63 and the angle of view 100.

Radii g' ffi Kinds of glass d -1O.6 "0-1. 5163 I-MJ) "I" 41-4. 46 Ila-1.U201 r-GOA "-16.84

iii-0. 6 nn-l. 7172 7-29. 5 n- 7.36

44-0. 5 flu-1.7172 r-29. 5 n- 0. 1886 h-(Lm "-10.84

(ll-4.46 flu-1. 8201 1 -60. I'm-11.26

(i -10. 6 flu-1. 5163 7-. 0 Til- When this objective is used forphotographing infinitely distant objects, the plate facing the object isnot required and may be dispensed with. The objective offers specialadvantages also in this case, since the intermediate error of 5distortion is especially insignificant.

I claim:

1. An anastigmatic objective for photography and projection, comprisingtwo pairs of meniscal members, each member being bounded by air, 10 andeach of the said pairs consisting of a diverging and a convergingmember, the one pair lying at the one and the other pair lying at theother side of the\locus of diaphragm; the diverging member of eacH pairfacing the locus of dia- 15 phragm and the concave surfaces of allmembers being turned toward this locus, those surfaces of each pairwhich face each other having different radii of curvature and thosesurfaces of the diverging members which face the locus of dia- 20 phragmbeing spaced at a distance greater than four fifths of the arithmeticalmeans of the ralii of curvature of these two surfaces.

2. An anastigmatic objective for photography and projection, comprisingtwo pairs of meniscal 25 members, each member being bounded by air andeach of the said pairs consisting of a diverging and a convergingmember, the one pair lying at the one and the other pair lying at theother side of the locus of diaphr m, the diverging 30 member of eachpair facing e locus of diaphragm and the concave surfaces of all membersbeing turned toward this locus, those surfaces of each pair which faceeach other having different radii of curvature and those surfaces of 36the diverging members which face the locus of diaphragm being spaced ata distance greater than the arithmetical means of the radii of curvatureof these two surfaces.

3. An anastigmatic objective for photography 40 and projection,comprising two pairs of single meniscal lenses which are bounded by airand each of the said pairs consisting of a diverging and a converginglens, the one pair lying at the one and the other pair lying at theother side of 45 the locus of diaphragm, the diverging lens of each pairfacing the! locus of diaphragmand the concave surfaces of all ensesbeing turned toward this locus, those surfaces of each pair which faceeach other having different radii of curva- 50 ture and those surfacesof the diverging lenses which face the locus of diaphragm being spacedat a distance greater than four fifths of the arithmetical means of theradii of curvature of these two surfaces, the refractive indices of thediverg- 65 ing lenses being greater than 1.65.

4. An anastigmatic objective for photography and projection, comprisingtwo pairs of single meniscal lenses which are bounded by air and each ofthe said pairs consisting of a diverging 60 and a converging lens, theone pair lying at the one and the other pair lying at the other side ofthe\locus of diaphragm,jthe diverging lens of each pair ac g e locus ofdiaphragm and the concave surfaces of all lenses being turned. 66 towardthis locus, those surfaces of each pair which face each other havingdifferent radii of curvature and those surfaces of the diverging lenseswhich face the locus of diaphragm being spaced at a distance greaterthan four 70 fifths of the arithmetical means of the radii of curvatureof these two surfaces, and the central thicknesses of these lenses beingsmaller than 2% of the focal length of the objective.

5. An anastigmatic objective for photography meniscal lenses which arebounded by air and each of the said pairs consisting of a diverging anda converging lens, the one pair lying at the one and the other pairlying at the other side of the locus of diaphragm, the diverging lens ofeach pair facing thellocus of diaphragmiand the concave surfaces of allenses eing urned toward this locus, those surfaces of each pair whichface each other having difl'erent radii of curvature and those surfacesof the diverging lenses which face the locus of diaphragm being spacedat a distance greater than four fifths of the arithmetical means of theradii of curvature of these two surfaces, the refractive indices of thediverging lenses being greater than 1.65, and the central thicknesses ofthese lenses being smaller than 2% of the focal length of the objective.

6. An anastigrnatic objective for photography and projection, comprisingtwo pairs of meniscal members, each member being bounded by air, andeach of the said pairs consisting of a diverging and a convergingmember, the one pair lying at the one d the other pair lying at theother side of the: locus of diaphragm) the diverging member of eaci paira ig the locus of diaphragm and the concave surfaces of all membersbeing turned toward this locus, these surfaces of each pair which faceeach other having different radii of curvature and those surfaces of thediverging members which face the locus of diaphragm being spaced at adistance greater than four fifths of the arithmetical means of the radiiof curvature of these two surfaces, the objective being symmetrical withthe exception of one pair of members whose two members lie equally tothe locus of diaphragm.

7. An anastigmatic objective for photography and projection, comprisingtwo pairs of meniscal members, each member being bounded by air, andeach of the said pairs consisting of a diverging and a convergingmember, the one pair lying at the one and the other pair lying at theother side of the locus of diaphragm, the diverging member of each pairfacing e locus of dia phragm and the concave surfaces of all membersbeing turned toward this locus, those surfaces M and projection,comprising two pairs of single 'SRFlfCll H00!!! each pair which faceeach other having different radii of curvature and those surfaces of thediverging members which face the locus of diaphragm being spaced at adistance greater than four fifths of the arithmetical means of the radii5 of curvature of these two surfaces, the objective having also at leastone lens which lies outside the said members and whose radii ofcurvature are, absolutely, greater than the focal length of theobjective. in

8. An anastigmatic objective for photography and projection, comprisingtwo pairs of meniscal members, each member being bounded by air, andeach of the said pairs consisting of a diverging and a convergingmember, the one pair lying 15 at the one and the other pair lying at theother side of thellocus of diaphragm the diverging member ofeach'Ta'aTir faicin'gthe locus of diaphragm and the concave surfaces ofall members being turned toward this locus, those sur- 20 faces of eachpair which face each other having different radii of curvature and thosesurfaces of the diverging members which face the locus of diaphragmbeing spaced at a. distance greater than four fifths of the arithmeticalmeans 28 of the radii of curvature of these two surfaces, 1 theobjective having also alplano-parallel plate! which lies outside thesaid members.

9. An anastigmatic objective for photography and projection, comprisingtwo pairs of meniscal members, each member being bounded by air, andeach of the said pairs consisting of a diverging and a convergingmember, the one pair lying at the one and the other pair lying at theother side of the @phrggm} the diverging 35 member of each pair facingthe locus of diaphragm and the concave surfaces of all members beingturned toward this locus, those surfaces of each pair which face eachother having different radii of curvature and those surfaces of 40 thediverging members which face the locus of diaphragm being spaced at adistance greater than four fifths of the arithmetical means of the radiiof curvature of these two surfaces, the objective having also twoexterior pl rallel 5 plates and being symmetrical tofi ifimdiaphragm.

ROBERT RICHTER.

